Tetrahedral block



FIG. 1 is a perspective view of a tetrahedral block, showing our newdesign;

FIG. 2 is a top plan view thereof, showing the vertical and horizontalsymmetry of the design;

FIG. 3 is a bottom plan view thereof, which is a mirror image of thefront elevation view;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a back elevation view thereof, which because of the verticaland horizontal symmetry of the design, is a mirror image of the frontelevation view;

FIG. 6 is a left side elevation view thereof, which because of thevertical and horizontal symmetry of the design, is a rotation from thefront elevation view;

FIG. 7 is a right side elevation view thereof, which because of thevertical and horizontal symmetry of the design, is a mirror image of theleft side elevation view;

FIG. 8 is another perspective view thereof;

FIG. 9 is another perspective view thereof;

FIG. 10 is another perspective view thereof;

FIG. 11 is another perspective view thereof;

FIG. 12 is another perspective view thereof;

FIG. 13 is another perspective view thereof;

FIG. 14 is another perspective view thereof;

FIG. 15 is a perspective view of a second embodiment of the tetrahedralblock, showing our new design;

FIG. 16 is another perspective view thereof;

FIG. 17 is another perspective view thereof;

FIG. 18 is another perspective view thereof; and,

FIG. 19 is another perspective view thereof.

CLAIM The ornamental design for a tetrahedral block, as shown anddescribed.